1. Field of the Invention
The invention relates to the connection arrangement of an immersion nozzle of refractory material and a spout, also of refractory material which are detachably connected for flow of liquid metal from the spout into the nozzle.
2. Description of the Prior Art
Immersion nozzles are generally used in the casting of molten steel or other liquid metals in cases where the casting stream must be shielded from the oxygen of the surrounding air. An example of this is the casting of steel from a ladle into the mould of a casting machine, but there are many other applications of immersion nozzles for similar purposes.
In a known arrangement, the nozzle is carried by a metal support ring which has projecting arms or spigots by which it is lifted to bring the nozzle into position relative to the spout. The spout is also supported by a metal ring.
Since immersion nozzles are subject to wear, it is important that they can be mounted simply and fast. However, it has been found that problems can arise in practice. Particularly, at the connection of the immersion nozzle to the spout, where both parts are made from a refractory material, there is a joint which is not completely air-tight. As a result of the high temperature of the spout and the nozzle during the casting of, for instance, steel, a completely air-tight joint is difficult to obtain. The under-pressure which prevails in the immersion nozzle during the casting thus leads to air being drawn in at the connection, which not only leads to the combustion of steel and alloying elements in the casting stream, with all the undesired metallurgical consequences thereof, but also to a local degradation of the refractory material. This degradation can finally lead to failure of the immersion nozzle.